How the heck can I use it if I can't boot into my Ubuntu desktop Gayan!, you... nutcase?

Well my friend, use your Live CD or Live USB... boot into your desktop using those media and simply instal the Boot-Repair using the same command. Or I think you should be able to run it in the "/usr/bin" directory if no internet connection is available. In that sense, we can actually create a Linux recovery disk/LiveCD by using this app that should help to access/recover our data without even losing a single byte! :D. Good luck.

It does looks like that the best thing to do before anything is to boot it up and make a backup of your "MULTIMEDIA" partition so if something happens the damage should be not that much.

If you are getting errors from I/O it might be because when you did your partitions been compromised. That happen also with me when I upgraded from Vista till win7 that it created it self new NTFS partitions and having problems with one logical partition where it used to be the ubuntu(thanks god not my /home)

After you manage to do your backup you can try out this commands in a terminal (I'm assuming that your ubuntu is in sda5)

and reboot your computer and it should load the ubuntu, after that you have to add your windows over the grub2 menu list, to do it so type in one terminal

sudo update-grub

I hope that you can solve your problem and you dosent need to reinstall everything again (including win). If you have to do it so I recommend to make you partitions physical and not logical how the windows does. There is many ways to create it partitions before installing the OS's. I recommend to have one HirensBoot always in hand. In this cd you can find all the kinds of tools that you might need to partitioned your HD and many, many others cool things